Troubleshooting guide

11-49
ATM and Layer 3 Switch Router Troubleshooting Guide
OL-1969-01
Chapter 11 Troubleshooting Layer 3 Network Connections
Troubleshooting IP and IPX Load Balancing
Step 7 Check the following:
• The VC identifier in the VPI and VCI columns matches the corresponding interface listed in the
show epc ipmcast command output shown in Step 4.
• The VC identifier listed in the X-VPI and X-VCI columns matches the entry for the corresponding
interface listed in the show epc ipmcast command output shown in Step 4.
If there are inconsistencies or non-zero invalid entries in the tables, you can use the clear ip mroute *
command to rebuild the tables.
Caution Use the clear ip mroute command carefully. It causes a temporary increase in switch router activity,
which can lead to traffic disruptions.
Troubleshooting IP and IPX Load Balancing
The Layer 3 enabled ATM switch router currently supports only two paths for IP and IPX. If there are
more than two paths in the FIB table the switch router uses the first two.
Note To reduce the number of unnecessary IPC messages, use a maximum paths statement of two for both
IP and IPX.
For IP: Load balancing is accomplished by using the Boolean function XOR on the least significant bit
(LSB) of the source and destination IP addresses. If the bit is set, use the second path; if not, use the first
path.
For IPX: Load balancing is accomplished by using the Boolean function XOR on the LSB of the IPX
source network and destination IPX network. If the bit is set, use the second path; if not, use the first
path.
By default IPX will only maintain one path in the IOS IPX routing table.
To get IPX to use more than one path use the global configuration command ipx maximum-paths
number.
Note Even if you set the ipx maximum-paths command number to a number greater than two the interface
module CAM still only maintains two paths.